In wireless systems and millimeter-wave communication systems in particular, establishing a wireless link between two nodes requires a line of sight (LoS) between the two nodes, as wireless signals in general are better received via LoS paths, and the high frequency millimeter-waves in particular have relatively weak diffraction properties and are therefore poorly adapted for bypassing obstacles blocking the line of sight. Therefore, when constructing a wireless network such as a millimeter-wave network, it is critical to understand the LoS condition between pairs of wireless nodes to be linked.